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端口无法从外部访问但显示正在监听

tag-icon • tag-icon networking server firewall
端口无法从外部访问但显示正在监听

我刚刚安装了 ubuntu 服务器 16.04 lts，这是一个带有 ssh 的基本服务器安装。

我安装了监听端口 { 443, 9900, 9901, 9997 } 的服务，它们似乎监听得很好：

$ netstat -plan --protocol=inet
(Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.)
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:9900            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:9997            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:9901            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN      -               
tcp        0      0 (serveraddress):53430     (serveraddress):9900      ESTABLISHED -               
tcp        0    388 (serveraddress):22        (myaddress):53994      ESTABLISHED -               
tcp        0      0 (serveraddress):9900      (serveraddress):53430     ESTABLISHED -

当我尝试从我的盒子外面连接它们时，连接被拒绝。

$ nmap -p22,443,9900,9901,9997 (serveraddress)

Starting Nmap 7.01 ( https://nmap.org ) at 2017-02-01 19:12 EST
Nmap scan report for IP-(serveraddress).static.fibrenoire.ca (serveraddress)
Host is up (0.014s latency).
PORT     STATE    SERVICE
22/tcp   open     ssh
443/tcp  open     https
9900/tcp filtered iua
9901/tcp filtered unknown
9997/tcp filtered unknown

Nmap done: 1 IP address (1 host up) scanned in 1.26 seconds

我没有激活防火墙

$ sudo ufw status
Status: inactive

出了什么问题？我需要做什么特殊的事情才能打开端口号 >= 1024？

答案1

原来我的服务器位于服务提供商控制的防火墙后面。我请他解除我需要的端口封锁。

这是正常现象吗？

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